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Message-ID: <20111123170004.GA23786@serge-laptop> Date: Wed, 23 Nov 2011 11:00:04 -0600 From: Serge Hallyn <serge.hallyn@...onical.com> To: Vasiliy Kulikov <segoon@...nwall.com> Cc: "Serge E. Hallyn" <serge@...lyn.com>, Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org, kernel-hardening@...ts.openwall.com Subject: Re: [RFC] Make Yama pid_ns aware Quoting Vasiliy Kulikov (segoon@...nwall.com): > On Wed, Nov 23, 2011 at 14:49 +0000, Serge E. Hallyn wrote: > > Quoting Vasiliy Kulikov (segoon@...nwall.com): > > > Actually, what concerns me is not ptrace, but symlink/hardling > > > protection. There is no interaction between namespaces in case of > > > containers via symlinks in the basic case. In case of ptrace I don't > > > think the child ns may weaken the parent ns - child ns may not access > > > processes of the parent namespace and everything it may ptrace is > > > already inside of this ns. > > > > Oh, yes. If you're saying the symlink protection shouldn't be > > per-pidns, I agree it seems an odd fit. > > > > How about a version of this patch leaving symlink protection > > out of pidns (maybe in user ns), and just putting ptrace > > protection per-pidns? > > I don't think moving symlink/hardling from pid ns to user ns is a good > idea as user ns is not matured yet. Also we (Openwall) want to use Yama > almost as-is in our RHEL6 and RHEL5-based kernels with OpenVZ support > which don't have user namespaces yet at all (yes, it is not a cause for > mainline decisions :-) ). > > While user ns is not yet ready, I don't clearly see what is the division > of security policies among namespaces including user namespace. I had > a view that all stuff related to processes (i.e. distinct processes in > several ways) belongs to pid ns, all net stuff to net ns, etc. If we > differentiate user ns and pid ns, only strictly things handling pids > (like kill(2), procfs, ptrace(2), etc.) belong to pid ns and all other > process-related stuff (like credentials handling, these symlink/hardling > things, etc.) belong to user namespaces. > > Can we probably leave them in pid ns for now and when user ns is matured > just move it from pid ns to user ns? Is it possible without breaking > Yama's ABI (I think so)? That's fine with me. thanks, -serge
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